SNVS520F August   2008  – November 2016 LM3686

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (Continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: Linear Regulator - LILO
    6. 7.6 Electrical Characteristics: Linear Regulator - LDO
    7. 7.7 Electrical Characteristics: DC-DC Converter
    8. 7.8 Electrical Characteristics: Global Parameters (DCDC, LILO, and LDO)
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 DC-DC Converter Operation
        1. 8.3.1.1 PWM Operation
        2. 8.3.1.2 PFM Operation
        3. 8.3.1.3 Internal Synchronous Rectification
        4. 8.3.1.4 Current Limiting
        5. 8.3.1.5 Soft Start
      2. 8.3.2 Linear Regulator Operation (LILO)
        1. 8.3.2.1 Start-up Mode
      3. 8.3.3 Current Limiting (LDO and LILO)
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Application Selection
        2. 9.2.2.2 Inductor Selection
          1. 9.2.2.2.1 Method 1
          2. 9.2.2.2.2 Method 2
        3. 9.2.2.3 External Capacitors
        4. 9.2.2.4 Input Capacitor Selection
          1. 9.2.2.4.1 CIN_DC-DC
          2. 9.2.2.4.2 CIN_LILO
          3. 9.2.2.4.3 CIN_LDO
        5. 9.2.2.5 Output Capacitor
          1. 9.2.2.5.1 COUT_DCDC
          2. 9.2.2.5.2 COUT_LILO
          3. 9.2.2.5.3 COUT_LDO
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 DSBGA Package Assembly and Use
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

1 Features

  • DC-DC Regulator
    • VOUT_DCDC = 1.2 V to 2.5 V
    • 600-mA Maximum ILOAD
    • 3-MHz Typical PWM Fixed Switching Frequency
    • Automatic PFM/PWM Mode Switching
    • Internal Synchronous Rectification
    • Internal Soft Start
  • Dual-Rail Linear Regulator: LILO
    • Load Transients < 50-mV Peak Typical
    • Line Transients < 1-mV Peak Typical
    • VOUT_LILO = 0.7 V to 2 V
    • 70-µA Typical IQ and 300-mA Maximum ILOAD
  • Linear Regulator: LDO
    • Load Transients < 80-mV Peak Typical
    • Line Transients < 1-mV Peak Typical
    • VOUT_LDO = 1.5 V to 3.3 V
    • 50-µA Typical IQ and 350-mA Maximum ILOAD
  • Combined Global Features
    • VBATT ≥ Maximum (VOUT_LILO + 1.5 V, 2.7 V)
    • Operates From a Single Li-Ion Cell or 3-Cell NiMH/NiCd Batteries
    • 100-µA IQ and 900-mA Maximum ILOAD

2 Applications

  • Mobile TVs, Hand-Held Radios
  • Personal Digital Assistants, Palm-Top PCs
  • Portable Instruments and Personal Clients
  • Battery-Powered Devices

3 Description

The LM3686 is a step-down DC-DC converter with a very low-dropout linear regulator and a low-noise linear regulator optimized for powering ultra-low voltage circuits. It provides three outputs with combined load current up to 900 mA over an input voltage range from 2.7 V to 5.5 V.

The device offers superior features and performance for many applications. Automatic intelligent switching between PWM low-noise and PFM low-current mode offers improved system control. During full-power operation, a fixed-frequency 3 MHz (typical), PWM mode drives loads from approximately 70 mA to 600 mA maximum. Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 28 μA (typical) at light load and system standby. Internal synchronous rectification provides high efficiency.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM3686 DSBGA (12) 2.435 mm × 1.687 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application

LM3686 30025501.gif